It is well known in the art that connective tissue is a major factor in variation of tenderness between different cuts of meat. Collagen, which is the dominant protein of connective tissue, emits blue-white fluorescence when excited with UV light at around the 370 nm range. There are several different biochemical types of collagen that differ in molecular structure. Of the two dominant types that occur in skeletal muscle and tendons, type I forms large unbranched fibres while type III forms small branched reticular fibres. Hence a meat probe coupled with a data processor capable of stimulating, measuring and analysing fluorescence from a cut of meat can be used in assessing meat tenderness.
The principle of connective tissues in meat fluorescing when exposed to a particular radiation wavelength has been known for some time as described by Swatland, H. J. Objective Measurement of Physical Aspects of Meat Quality, Reciprocal Meat Conference Proceedings, Vol. 42, 1989. Initial investigations in the development of a probe, which is capable of both exciting and collecting fluorescence from connective tissue in meat, are described in Swatland, H. J. Analysis of Signals from a UV Fluorescent Probe for Connective Tissue in Beef Carcasses, Computers and Electronics in Agriculture (6, 1991) 225:218 and Bidirectional Operation of a UV Fluorescent Probe for Beef Carcass Connective Tissues, Computers and Electronics in Agriculture (7, 1992) 105:300, both of Elsevier Science Publishers B. V. Amsterdam. The original probe was an adaptation of a fat depth probe used by the Danish Meat Research Institute in Denmark for measuring the depth of fat on pig carcasses. The probe was adapted by the use of an optical fibre which was inserted in the device. The fibre was cut at an angle so that the interface optics were asymmetrical. Exciting radiation was supplied in the optic fibre from a 100 watt short arc mercury source directed through a heat absorbing filter, a red attenuation filter and a dichroic mirror. Light peaking at 225 nanometres was directed into the proximal end of the optic fibre with a microscopic objective. Fluorescent from the connective tissues in contact with the optical fibre of the probe was measured through the dichroic mirror at the proximal end of the fibre with a flat response silica detector and a radiometer. The dichroic mirror was used as a chromatic beam splitter to separate the outgoing excitation light at 225 nanometre from the incoming fluorescent emission at a wavelength considerably greater than 225 nanometre. A depth measurement device for measuring the depth to which the probe was plunged into the carcass was provided either by an optical shaft encoder to trigger photometer measurements at set increments through the carcass, or a continuously variable analogue device, such as a potentiometer. The operation of the potentiometer can be affected by temperature.
The positioning of the glass optic fibre in the probe was also suggested, instead of being cut at an angle, of being slightly bent or rounded in conjunction with a plurality of additional thin fibres as described in the article by Swatland, H. J., Bi-directional Operation of a UV Fluorescence Probe for Beef Carcass Connective Tissues Computers and Electronics in Agriculture 7(1992) 105:300. The use of the multiple fibres around the glass optic fibre was to gather additional information in respect of shape of the connective tissue as the probe passed by the connective tissue. Extensive analysis of the collected fluorescence from use of the meat probe is described in several papers by Swatland in Food Research International which include Correction for Baseline Drifting in Probe Measurements of Connective in Beef, Food Research International 26, 1993 371:374; An Anomaly in the Effective Temperature on Collagen Fluorescence in Beef, Food Research International, 26, 1993 271:276 and Correlations of Mature Beef Palatability with Optical Probing of Raw Meat, Food Research International, Vol 10, No. 4, pp 403-446, 1995. Swatland also published with others in Swatland et al., An Effective Connective Tissue on the Taste Panel Tenderness for Commercial Prime Beef Detected with a UV Fibre Optic Probe (cite to be inserted) and UV Fibre Optics Probe Measurements of Connective Tissue in Beef Correlated with Taste Panel Scores for chewieness, Food Research International, Vol 10. No. 1, pp 23-30, 1995.
Data collected from a meat probe plunged in a carcass usually includes at least two parameters: depth of insertion of the probe and level of fluorescence. Once this data has been obtained, it is necessary to present it in some meaningful manner. Since data presented in table form can be difficult to comprehend, the typical method of display is to use graphical display with depth of penetration on the x axis and level of fluorescence on the y-axis. When viewing data obtained in this way, the graph forms a number of peaks and valleys of varying height and widths. The data will vary from sample to sample in amplitude and variation of amplitude from different positions on the carcass, as well as from carcass to carcass. It was thought that a comparison of the number of peaks, height of peaks, frequency of peaks and width of peaks for various samples of meat all on the same scale allowed one to assess tenderness by virtue of these characteristics. It was generally understood that a print-out of these characteristics, which shows a relatively smooth line, indicated tender meat. Presenting the above characteristics of the fluorescent data always at the same scale was believed to be more than sufficient in assessing and evaluating the information in establishing tenderness. We have now discovered that changing the scale for the representation of the data provides useful information in evaluating meat tenderness. It has been found that, in changing the scale, there is useful information in respect of the number of peaks, height of peaks, frequency of peaks and width of peaks where in the scale which normally accommodated tougher pieces of meat, the representation would in essence be flatline.